Since a lack of thought was put into Applejack's argument with Princess Celestia about who would own Applementium Industries, and quite frankly all of Equestria, the Princess was preparing a government force to try and subdue Ponyville before Applejack became too powerful. Applejack, on the other hand, was nowhere near ready for even an assault of bunnies. But to her luck, after warning about the upcoming situation, all the ponies were convinced that life would be worse if Applementium Industries was under government control. If that were to happen, Princess Celestia would once again have total control over each and everypony's lives, considering she would own Applementium and all the businesses that thrive around it. The ponies of Ponyville all agreed that it was time to prepare. Applejack may not have had weapons, but two things were for sure. She had access to the strongest metal in the land, and she had the full support of her friends.
The Princess had an army that was almost mobilized, so the Ponyville had to act fast. They had to work together and make weapons that could could use each pony's full power. Pegasi were best suited for scouting and dropping bombs. The unicorns could use their magic to operate projectile weaponry, while the earth ponies could fight in the front line, produce munitions, or grant medical aid. Ponies have had explosives for a long time, but they were usually used for mining. It was time to crack open each and every last crate of boxes and manipulate them to be dropped or projected before exploding. The first day of making munitions was hard, and none of the ponies had even tested to see if they worked. With no opposition in sight, they tested each time of shell to find the best. Applementium could not be used as a missile just because of how durable it was, so they stuck with iron shells. Timed explosives were unwieldy, so they had to use fragile rounds that contained two different chemicals that would explode on contact. After discovering the perfect bullet, it took hours to even make 100 shells, which was obviously insufficient.
"Why is it taking so long to make these tiny shells? We need to move faster if we want to even stand a chance against a magic-powered army!" ordered Applejack.
The workers explained, "We can't construct any faster! Some of us don't remember how to make a full bullet, and some are just not that fast!"
"Well, there is a simple solution so that we can get 1000 shells in half the time," said Applejack.
"What do we do?" asked the workers.
Applejack responded, "Simple. All you ponies need to do is split the labour. Divide into stations. One station makes the cartridge and then passes it to the next station, who will add the explosives. Then the round is passed to the final station, who will finish the bullet. Does that sound easier?" And it certainly was easier. At first, the ponies were not used to splitting jobs, but once the had adapted to the change, an assembly line was created, punting out dozens upon dozens of shells in almost half the time. Other task forces caught on and designed bombs and tools just as fast. Applejack and her genius had once again given them and advantage.
As well as weaponry, the ponies needed fortifications. Unlike in the shells, Applementium was the perfect for this job. Applementium hedgehogs and barbed wire were placed around the town, as well as plating over the buildings to give a makeshift areal shield. With the assembly line, massive cannon towers were being constructed in a matter of days. They even fitted the railways with locomotives armed with rail-bound cannons to scout around the city, fire, and drive away. Twilight Sparkle then devised a similar tactic: she fitted tracks to the locomotives to form belt mechanisms so that the locomotives could drive over land. The body of each train was replaced with an Applementium casing, with sides completely covered by cannons. Twilight had brought mounted warfare to the next level. in about a month, the residents of Ponyville were prepared for battle.
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Even with all these innovations, the opposing side was also devising some of their own military advantages. For one thing, Princess Celestia was going to darken the sky during the invasion, which no pony else could do. She also remodeled some of the airships to act as floating fortresses. She knew (because of spies) that Ponyville did not arm the pegasi with anti-air weaponry. Their jobs were to bomb, so the Princess had the whole sky to herself. Other than air vehicles, she had nothing much else in terms of mechanics. But what she lacked in weapons she compensated with training. Unlike the ponies, the Royal Elite was the best trained fighting force even in Canterlot. They were trained to ambush the enemy, and with the darkness by their sides, they had the potential to defeat Applejack singlehoovedly.
While Ponyville was preparing for attack, the Princess already stationed her army around the city. The unicorns implanted massive siege cannons into the ground while pegasi flew at high altitudes dropping time-arming mines into the ground below them. As for countering Twilight's tanks? The Princess had no anti-tank weaponry. Even the cannons were based on magic, not combustion. What she did was was heavily train her unicorns with moving heavy moving objects. A well trained unicorn could wipe a path between even a whole army of tanks, walk through, and move the tanks back in place. She had nothing to counter the Applementium fortifications, so she was now even more reliant on the unicorns being able to maneuver around the defenses.
The Princess had an elite infantry force at her command, while Applejack had a clumsy steal wall under her hooves. No one in Ponyville had any experience with fighting. Twilight insisted that the tanks move in one at a time to stall the enemy without wasting too many. Rarity ordered for colourful uniforms so that no one would confuse the enemy with the ally. Rainbow Dash was confident enough that her bomb squadron would not face any areal opposition. Pinkie was smart enough to order for a stationary army behind the safety of the walls, but that was a no-brainer. Fluttershy was not willing to partake in any aspect of the battle. The stupidest decision was Applejack agreeing that these were all good ideas. With this unintelligent of military planning, Ponyville was heavily reliant on the performance of Applementium.
So, why was a war even necessary? The answer is that it wasn't. Applejack was earning power, while Princess Celestia was losing power. Both needed their positions and could not afford to sell them. But was war mandatory? Fluttershy asked this question. "What is wrong with settling an argument with a simple board game ore something," thought Fluttershy. "Why even disagree with something in the first place? Couldn't Applejack keep her factory yet still help the Princess retain the loyalty of her subjects. This could all have been better if the two would have worked together." But with Fluttershy's personality, there was really nothing she could do, except evacuate the children and animals.